This invention relates to a lightweight engine block having a hybrid cooling system that in part utilizes water cooling and in part utilizes air cooling to maintain normal thermal operating conditions in an engine. The lightweight engine block is a unitary casting that is fabricated from a thermally conductive material such as aluminum and is cast with one or more cylinders. Each cylinder is formed with a cylinder wall having an upper cylinder section with an outer housing wall displaced from the cylinder wall around the upper cylinder section forming a reduced-capacity, annular water jacket. A lower cylinder section has a plurality of outwardly directed cooling fins that project from the cylinder wall in alignment with the axis of the cylinder to both cool the lower portion of the cylinder and stiffen the fabricated casting.
Developing high performance, lightweight engines for use in automotive and other applications where fuel efficiency is a concern requires an integration of many diverse design factors from the outward configuration of a vehicle to reduce wind resistance, to the optimization of the vehicle power-weight ratio to enable an engine with the necessary power to drive a vehicle of a given weight. Although reduction in the weight of the engine does not affect engine performance for stationary power systems, where engine weight reduction is achieved in part by reducing the size and power consumption of auxilliary components, such as engine driven cooling water pumps, then operating efficiencies can rise in stationary as well as automotive systems.
Therefore, design of both the of the engine and its auxiliary components becomes an important factor in determining the performance criteria of the engine.
It is the object of this invention to provide an engine block that integrates a liquid cooling system with an air cooling system such that reduced capacity radiator, pump and conduit components can be utilized with the block when assembled into an operating engine. The engine block devised has particular application in a lightweight fuel efficient vehicle, but may also be used as a stationary power source for electrical generation or other use where fuel-efficiency is desired.